1. Field of the Invention
The present invention relates generally to railway car body underframes for mounting on a bolster of a supporting truck, and more specifically to center filler plates for use with draft sills of such underframes.
2. Description of the Prior Art
Conventionally, the entire weight of railway freight cars is carried on two spaced circular center plates on railway car draft sills. These center plates engage two mating female bowls on cooperating truck bolsters. The trucks include wheel sets, which support the freight car on the railroad track.
Conventional draft sills have been either fabricated or cast of steel. In some cast steel draft sills, the center plates are cast as an integral part of the draft sill. In some other cast draft sills and in conventional fabricated draft sills, a separate center filler plate is welded or bolted to the draft sill. These center filler plates have been advantageous in that they can be removed and replaced as they become worn without requiring replacement of the entire draft sill.
The conventional center filler plates have included base portions that are received within the draft sill above a flange. The flange is typically welded to the outside of the draft sill. Exposed below the flange is the center plate bowl bearing surface that is received within the center plate bowl on the truck bolster. Above the center plate bowl bearing surface is a central hub to receive a part of a king pin when the draft sill is mounted on the car truck. Also above the flange and surrounding the central hub is a generally rectangular outer web connected to the central hub through four spaced ribs. The web and the ribs provide stiffness to the center filler plate to withstand stresses from the vertical loads and the compressive loads from the railway car body bolster. Deep pockets or recesses are defined by the hub, the ribs and the sides of the web.
For handling the center filler plates, prior structures have included feet formed at the corners of the box or outer web to allow for stacking of the center filler plates as well as to provide openings between the feet so that workers could fit their hands in for lifting each center filler plate.
Conventional center filler plates have been made of cast steel. In such casting operations, the deep pockets or recesses in the center filler plate are defined by green molding sand from which the casting must be removed after the casting has cooled. Commonly, identifying marks are cast into the center filler plate in the vicinity of the pockets or recesses.
Finishing the cast center filler plates has been problematic. At casting temperatures, the sand may become burned in, that is, the silica of the molding sand becomes very hard. The burned in sand does not fall out with shaking of the casting, and can ruin cast markings. Removal of burned in sand is a labor intensive operation.